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                [Usaco2004 Open]MooFest 狂欢节                </h1>
                <p>时间限制：1s&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;  空间限制：128MB</p>			</div>
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                                <h3>题目描述</h3><p><div><span style="font-size: medium">&nbsp;&nbsp;&nbsp;&nbsp;每一年，约翰的N(1&le;N&le;20000)只奶牛参加奶牛狂欢节．这是一个全世界奶牛都参加的大联欢．狂欢节包括很多有趣的活动，比如干草堆叠大赛、跳牛栏大赛，奶牛之间有时还相互扎屁股取乐．当然，她们会排成一列嚎叫，来欢庆她们的节日．奶牛们的叫声实在刺耳，以致于每只奶牛的听力都受到不同程序的损伤．现在告诉你奶牛i的听力为vi(l&le;Vi&le;20000)，这表示如果奶牛j想说点什么让她听到，必须用高于vi&times;dis(i，j)的音量．而且，如果奶牛i和j想相互交谈，她们的音量必须不小于max(Vi，Vj)&times;dis(i，j).其中dis(i，J)表示她们间的距离．</span></div>
<div><span style="font-size: medium">&nbsp;&nbsp;&nbsp;&nbsp;现在N只奶牛都站在一条直线上了，每只奶牛还有一个坐标xi(l&le;xi&le;20000)．如果每对奶牛都在交谈，并且使用最小音量，那所有n(n-1)/2对奶牛间谈话的音量之和为多少？</span></div></p><hr/><h3>输入格式</h3><p><div><span style="font-size: medium">&nbsp;&nbsp;&nbsp;&nbsp;第1行输入N，之后N行输入Vi和xi．</span></div></p><hr/><h3>输出格式</h3><p><div><span style="font-size: medium">&nbsp;&nbsp;&nbsp;&nbsp;输出音量之和．</span></div></p><hr/><h3>样例输入</h3><pre>4
3  1
2  5
2  6
4  3
</pre><hr/><h3>样例输出</h3><pre>57
</pre><hr/><h3>提示</h3><p>没有写明提示</p><hr/><h3>题目来源</h3><p>Green</p>
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